In the field of chain drive systems for vehicles, torsionally compliant sprockets can be used to isolate chain drives from torsional vibrations. Compliant sprockets can include a resilient element to introduce some compliance between the sprocket shaft and the chain or gear. The resilient element acts as a mechanical low-pass filter that reduces the intensity of the torsional vibrations experienced at the chain or gear relative to those at the sprocket shaft. Typical designs include a sprocket split into inner and outer or front and rear parts that are connected by a resilient element such as a torsion spring. Known designs tend to be constrained by performance requirements at engine idle, because the firing order excitations are close to the resonant frequency of the chain-sprocket system at low speed.